1. Field of the Invention
This invention relates to recording or reproducing apparatus, and more particularly to a mechanism for bringing a record bearing medium into resting engagement on the coupling portion of the apparatus.
2. Description of the Prior Art
There have been known a wide variety or apparatus for recording or reproducing informations by using, for example, rotating magnetic discs as the record bearing medium. In such apparatus it is required to set the record bearing medium on the coupling portion or spindle of the apparatus accurately and reliably. That is, if setting of the record bearing medium is imperfect, as information is then recorded on eccentric tracks to the axis of rotation of the spindle, it will result that when the record bearing medium is transferred to, and reproduced by another apparatus, the track cannot be well traced. Also an accidental inclination of the record bearing medium to the spindle fails to assure good contact of the head with the medium, thus leading to some possibility of occurrence of errors in signal transformation between the head and the medium, and damages of the head and medium.
Attempts have been made to eliminate the above-described drawbacks by applying pressure to the record bearing medium as it is loaded on the rotating spindle of the apparatus, or by using a tapered form of the spindle, so as to reduce the possibility of occurrence of the above-described eccentric settings. For this purpose, means is provided for locating the record bearing medium in a prescribed position, taking, for one example, the form of a permanent magnet piece and a magnetizable member, one of which is put on the rotating spindle and the other of which is mounted on the core of the medium so that an attractive force exerted therebetween can bring the medium into resting engagement on the spindle. Another example is to use a mechanism having pressing means arranged upon preliminary loading of the record bearing medium to proceed the loading by forcibly pushing said medium against the spindle and then upon recording/reproducing to rotate as a unit with said medium, or to maintain the contacting state.
In the former case or the method using a permanent magnet, however, there is need to increase the attractive force of the permanent magnet sufficiently. This calls for an increase in the volume of the permanent magnet, or an expensive magnetic material selected from the rare earth group has to be employed. Further, increasing of the attractive force of the permanent magnet has a limitation for the record bearing medium in the form of the magnetic disc, because the much-desired increase in the magnetic force gives appreciable influence to the recording/reproducing of the information. Also in the latter case, since the pressing means, even after having set the record bearing medium on the spindle, is left in engagement with the medium during the recording or reproducing operation, and this places a load on the spindle, accurate control of the rotation of the record bearing medium becomes difficult to achieve. Particularly in application to the type of recording or reproducing apparatus which uses small-sized rotating magnetic discs, this problem becomes serious.
Apart from this, in the apparatus of the type described above, from consideration of speeding up the recording or reproducing, it would be very advantageous that the sure resting of the record bearing medium on the spindle is immediately followed by automatic setting of the recording or reproducing head in a predetermined start position, or initiation of a recording or reproducing operation. This aspect is very important particularly for the still picture recording apparatus such as the still video camera in view of reducing the possibility of missing the recording chance (corresponding to the so-called "shutter chance" for the known film camera).
Further apart from the above, where the record bearing medium is housed in a container called cassette, jacket, or pack (hereinafter abbreviated as cassette), there has been made a proposal for allowing the cassette to partly project itself outwardly of a chamber therefor within the casing of the recording or reproducing apparatus in automatic response to actuation of a removal control member so as to facilitate the removing operation of the cassette from the recording or reproducing apparatus. To achieve this, for example, ejecting means is used which comprises a spring or other suitable resilient member on which power is stored when the cassette is inserted into the chamber. When the cassette is to be removed, the bias force of the spring expels a portion of the cassette out of the apparatus.
By the way, the use of such means often leads to such an accident that when the operator removes his hand from the cassette in the fully inserted position, the cassette jumps out of the apparatus due to the action of the bias force of the resilient member. It is, therefore, desirable to employ means for holding the cassette in a prescribed position when the cassette is fully inserted. To this end, it has been proposed to construct the holding means in the form of a latch arranged to act on the cassette when it is fully inserted into the chamber, so that the cassette is prevented from ejection. With the use of this latch member, however, it becomes necessary to additionally use some means for releasing the cassette from the latching connection when the cassette is to be ejected. Then, it has been proposed that an actuator for this latch release means is arranged to operate either when a cassette removal control member is operated, or when the cassette chamber moves to the recording or reproducing stage.
However, the former arrangement tends not only to increase the complexity of structure of the necessary linking mechanism, but also to produce a difficult problem that the timing of displacement of the cassette chamber or the outer cover to the cassette take-out position is properly related to the timing of the releasing of the cassette from the latching connection. If the timing relationship is incorrect, there will occur an accident that the cassette chamber reaches the take-out position before the cassette is released from the latching connection so that the cassette is no longer taken out. Also the latter arrangement has a difficult problem of the accuracy of the releasing position of the release member provided in the body of the recording or reproducing apparatus. If this is not accurate, the cassette will be released from the latching connection before the cassette chamber reaches the recording or reproducing stage so that the cassette is no longer set in the prescribed position.